Poly (Isobutylene‐alt‐Maleic Anhydride) With Pendant Benzoxaborole: Dynamic Covalent Interactions at Physiological pH and Antibacterial Properties

Boronated polymers have proven great potential and versatility for a variety of applications. In this work, poly (isobutylene‐ alt ‐maleic anhydride) (PIMA) is chemically modified with benzoxaborole to yield the anionic boronated polymer, PIMA‐Bx, a bifunctional dynamic covalent material operative at physiological pH. Benzoxaborole is incorporated into the polymer backbone via a spontaneous ring opening reaction followed by basic hydrolysis. Affinity studies with model ligands and a custom synthesized glycopolymer derived from PIMA are performed using fluorescence spectroscopy and microscale thermophoresis (MST), confirming full accessibility to benzoxaborole binding sites and pH modulation of the BO interaction. Supramolecular assemblies between complementary PIMA polymers are studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM), revealing nanosized structures modulated by pH changes in the range 5–7.4. In vitro cell experiments demonstrate excellent biocompatibility of PIMA‐Bx with cultured cells even at very high concentrations. Furthermore, fluorescence confocal microscopy (CLSM) confirms successful internalization of the benzoxaborole‐grafted PIMA in HeLa and A549 cells. The boronated polymer also exhibits antibacterial activity per se against typical Gram‐negative Escherichia coli and Gram‐positive methicillin‐resistant Staphylococcus aureus . Therefore, this new boronated polymer, which is easily prepared using cost‐effective materials, is an attractive material for biomedical and pharmaceutical applications.